Technological advancements have enabled portable computers to be built in various forms such as notebook, tablet PC, and personal digital assistants (PDA). Some of these forms can be unified into one single portable computer with multiple configurations.
Portable computers or notebooks typically comprise of a computer base and a display screen. The computer base generally holds the central processing unit, memory, electronic circuitry and other components, such as a keyboard, a disk drive. Typically, the base is hinged to the display in a manner in which the display folds down on the base, as shown by the computer (900) in FIG. 5. This design is referred to as the clam shell type enclosure. The display screen is typically connected to the base in such a way that the screen is hidden when the clam shell is closed. That is, the screen faces the upper side (typically, the keyboard) of the base.
There are several disadvantages of the clam shell design. One disadvantage is that the screen and the keyboard are next to each other. If the screen is placed at a comfortable viewing position, it will make the arms and shoulders uncomfortable for typing. On the other hand, if the computer is placed at a comfortable typing position, it would make the neck uncomfortable when looking at the screen. This problem can cause serious computer-related work injuries. Another disadvantage is that it needs to sufficient room to fully open the clam shell computer and position the display screen at an angle of about ninety (90°) or more with respect to the base for normal viewing; and this can be very difficult when operating in tight space, such as on the pull-out tray on the back of a declined airplane seat. Therefore, the clam shell design is insufficient for comfortable use.
In general, it is useful to be able to arrange a single portable computer into various configurations as follows.                (1) Improved Notebook configuration: The display screen can be adjusted to a desirable viewing angle, and to a position by height (up or down relative to the base) and by depth (forward or backward relative to the base's user edge).        (2) Shared viewing configuration: This is configuration (1) plus display adjustment by width (left or right of the space above the keyboard). (This can be useful when more than one people are looking at the screen at the same time.)        (3) Tablet PC configuration: The portable computer is closed with the base stacked underneath the upward-facing screen to be used as input pad. (The keyboard in this configuration can either be facing down or up. But it does not matter.)        (4) Stylus input configuration: The portable computer is open with screen up in normal viewing position; but the bottom side (opposite to the keyboard) of the base is up and used as input pad.        (5) Space saving configuration: The portable computer is closed with the display stacked underneath the base, so that the base can be used as a desktop machine together with a desktop display unit, typically with a bigger and better screen.        (6) Desk note configuration: The display is completely detached from the base so that the base can be used as a desktop machine together with a desktop display unit. (Both this configuration and the Space saving configuration can get the built-in display out of the way of the desktop monitor screen.)        
There have been numerous attempts to address various subsets these six configurations. Many of them are focused on the screen viewing position adjustment using various approaches, which are all different from the multi-sectioned arm approach in the present invention. Some others are focused on mode transitioning between conventional notebook and tablet PC. There has been no single invention until now that can solve all six configurations in a single computer.
The purpose of the present invention is to support all or a subset of configurations (1)–(6) in one single portable computer. The invention also has some additional features.